The invention relates to packaging and shipping systems and in particular to packaging of materials and items to be secured as a unit load or to be secured to a shipping and transporting means, such as a pallet or slip sheet. Specifically, it relates to such systems using plastics stretch film (a high cling film) as the binding and securing agent.
A need has existed for some time for a simple and economical means for applying plastics stretch film material. A copending application of the present invention, Ser. No. 914,801, filed June 12, 1978, now U.S. Pat. No. 4,179,081, entitled "System For Application of Plastics Stretch Films" solved part of the problem and provided a simple and economical means to do the work. However, several problems remained and the present invention, solves the remaining problems. The apparatus may be used for manual or machine application of the film.
In the prior art two methods are available for applying the plastics stretch film material to materials and units to be packaged or secured as hereinbefore described.
One method is to use a very expensive automatic machine to hold a supply of the plastics stretch film and to automatically wrap it around the unit of materials to be packaged; and to secure the unit of materials to a shipping or transporting means. Such machines require the attention of an operator and they do have their own limitations.
Another method is to use a commercial manually operated grabbing or holding device. However, this manually operated device is very expensive in comparison to the cost of the present invention. The commercial device is difficult to adjust to obtain the wide range of speeds and tensions that are required while manually wrapping the plastics stretch film to a unit load. The adjusting system on the commercial unit is such that it is difficult to "feel" the fine line between "full stop" and "just barely moving". As a result, many broken films are encountered during use of the commercial unit. The aforementioned copending application solved some of the problems. The present invention eliminates these other problems and is extremely simple to operate.
One of the devices in the prior art consists of a shaft means passing through the tubular core of the roll of plastics film material. The shaft has more or less "D" shaped hand grips on each end that are held by the operator and used to pull the plastics film around or over the unit or load being packaged or secured. When more tension is to be placed on the plastics film, one of the two hand grips is twisted to tighten the shaft movement through the core of the roll of plastics film. This tightening by twisting one of the hand grips does not provide a sensitive "feel" in the operator's hands and is the cause of the frequent breaking of the plastics film mentioned hereinbefore.
Another of the devices in the prior art consists of a shaft means passing through the aforementioned tubular core of the roll of plastics film material. The shaft also has more or less "D" shaped hand grips on each end as hereinbefore described, but the tension adjustment is provided by a brake-nut on the end of the shaft. Changes in the need for more or for less tension requires the operator to use one hand to operate the brake-nut while holding the roll of plastics film with the other hand in one of the "D" shaped hand grips. This method of adjusting the tension is an awkward operation to perform. In addition, this method also causes frequent breaks of the plastics film. Other prior art methods apply friction to the edges of the cores, such as using a leather pad, a metal cone, and similar systems.
In the aforementioned copending application and in the present invention the control of the amount of tension is by the direct pressure or the squeeze of the operator's hands on the flexible tube-like devices around adapter extended ends of the core of the roll of plastics material. Two embodiments in the copending application and two embodiments in the present invention are provided for extending the core ends of the roll of the plastics material, however, the tension control means is the same in each case.
In the prior art the fixing of the device to a roll of plastics stretch film required considerable time and effort to insert a shaft through or to drive a toothed or spiked shaft into the ends of the core of the roll of plastics stretch film, and then add hand grips, holding or securing nuts, and other such mechanical operations. In the copending application, the preparation is primarily the slipping of two flexible hand grips on the ends of the core of the roll of plastics stretch film or on simple inserts in the core. Several problems still remain and in the present invention these problems are solved as hereinafter described.
One problem concerns the fusing together of the ends of the last wraps of the plastics film on the supply core by the heat of the friction of the braking unit rubbing against the exposed ends of the roll of plastics film as the roll turns while film is being applied. This usually occurs in connection with rolls of film on small diameter cores. Loss of film stock through fused ends usually amounts to 10 to 30 linear feet, a considerable wastage. Once fused, the film tears, rather than breaking loose. Heat sealing one end of the braking unit partially solves the problem.
The present invention eliminates this problem by the first embodiment provided. It provides an insertable adapter for the small diameter cores which moves the edges of the braking unit down below the external surface of the supply core. It thus avoids friction against the exposed edges of the film on the supply core and consequently eliminates frictional heat that fuses the ends of the film together.
The adapter utilizes a rubberized or rubber-like or friction generating material means to frictionally attach it to the inside diameter of the supply core.
The other problem is that with large diameter supply cores, the use of wedge-type adapters distorts the ends of supply cores which renders the cores unsatisfactory for reuse and often destroys the recycling possibility. In addition, the wedge-type adapter is often difficult to remove from the core.
The present invention eliminates this problem by the second embodiment which provides for an insertable adapter having a plurality of both internal and external nodes that have a flexibility to assist in making the insertion. The external nodes interfacing with the surface at the internal diameter of the supply core, and the internal nodes interfacing with the surface at the external diameter of the insertable adapter used for control.
The details of both of these embodiments of the present invention are described in the specification hereinafter.
It is, therefore, an object of the invention to provide an apparatus for applying plastics stretch film to a unit that is economical to manufacture and simple to operate.
It is another object of the invention to provide an apparatus for applying plastics stretch film to a unit that permits the operator to "feel" the movement and tension condition through the hands on the device of the system.
It is yet another object of the invention to provide an apparatus for applying plastics stretch film to a unit that consists of two simple flexible hand grips for control.
It is a further object of the invention to provide an apparatus for applying plastics stretch film to a unit that does not require the operator to remove the hands from the device to change the tension setting.
It is still another object of the invention to provide an apparatus for applying plastics stretch film to a unit that prevents fusing of the ends of the plastics stretch film on the supply core.
It is also an object of the invention to provide an apparatus for applying plastics stretch film to a unit that has a flexibility of adaptation to a range of supply cores which is easy to insert and reuse without damage to the supply core.
It is also another object of the invention to provide an apparatus for applying plastics stretch film to a unit either manually or mechanically.
Further objects and advantages of the invention will become apparent in the light of the following description of the preferred embodiments.